1. Field of the Invention
The present invention relates to a burglar-proof system for a vehicle used to prevent theft mainly in an automobile.
2. Background Art
Recent years, there has been an increasing number of vehicles each incorporating a vehicular burglar-proof system for preventing theft of articles inside of the body or cabin of a parked vehicle by flashing the headlights or blowing the horn when a door of the vehicle is unlocked or opened/closed by a forged key or tools.
A conventional vehicular burglar-proof system is described with reference to FIG. 5.
FIG. 5 is a block diagram of a conventional vehicular burglar-proof system. In the drawing, lamps (headlights) 1A for radiation of light in the front direction of a vehicle, buzzer 1B installed in the cabin of a vehicle, and alarming horn 1C form alarm unit 1.
Further, the system includes door knob 2A for opening/closing a door, locking knob 2B for locking/unlocking the door, key cylinder 2C for receiving a key when the engine is started. Each of these components has a switch for detecting the movement or opening/closing of the component and form detection unit 3.
Then, these alarm unit 1 and detection unit 3 are electrically connected to control unit 4 of the vehicle formed of electronic components, such as microcomputers, to form a vehicular burglar-proof system.
Cntrol unit 4 has changeover switches each for selecting one from a plurality of alarm unit 1. In FIG. 5, three changeover switches are provided. Changeover switch 41 is a switch for determining whether or not to select lamps 1A as an alarm unit. Changeover switch 42 is a switch for determining whether or not to select buzzer 1B as an alarm unit. Changeover switch 43 is a switch for determining whether or not to select horn 1C as an alarm unit. When a changeover switch is turned on (energized), a predetermined alarm unit is selected. When a changeover switch is turned off (not energized), a predetermined alarm unit is not selected. In FIG. 5, only horn 1C is selected by changeover switch 43 as an alarm unit.
In a vehicle incorporating a so-called keyless entry system in which a driver holds a card or a portable unit including a key (not shown) and locks/unlocks doors by communication between the card or the portable unit and a vehicle, a communication unit (not shown) for communicating with the portable unit held by the driver is provided in the vehicle. The communication unit is connected to a drive unit (not shown) for operating locking knob 2B, such as a motor, and to control unit 4.
To prevent theft, predetermined alarming states, such as flashing lamps 1A, sounding buzzer 1B, and blowing horn 1C, are set in control unit 4.
In the above structure, when a driver operates the portable unit, or goes at a predetermined distance away from the vehicle after getting off the vehicle and closed the door, an inherent code is transmitted, as a radio signal, from the portable unit to the vehicle. Then, the communication unit in the vehicle receives the code and determines if it is a correct code inherent to the vehicle or not. When the code is correct, the drive unit, such as a motor, operates locking knob 2B and locks the doors.
When a driver comes near to the vehicle and operates the portable unit, or enters within a predetermined range of distance from the vehicle, the portable unit transmits a radio signal similarly. Then, the communication unit receives the signal, and the doors are unlocked.
Further, when a driver leaves a parked vehicle with its doors locked, and a person other than the driver opens/closes or unlocks one of the doors using a forged key or tools, detection unit 3 detects that the door is opened/closed, door knob 2A is operated, or locking knob 2B is unlocked even though communication is not made between the communication unit and the portable unit. Control unit 4 detects this detection.
Then, control unit 4 operates to provide a predetermined alarming state, such as blowing horn 1C. This draws attention of surroundings and prevents theft in a parked vehicle.
Known as one of prior art references of this application is Japanese Patent Unexamined Publication No. H07-47928.
However, in the conventional vehicular burglar-proof system, the alarming state is predetermined, such as blowing horn 1C only. For this reason, to select individual alarming states according to the use of the driver of a vehicle, the changeover switches of alarm unit, i.e. lamps 1A, buzzer 1B, and horn 1C, are required. This increases the number of constituent components of the burglar-proof system. Further, because changeover switches are generally provided in obscure and user-unfriendly positions, changeover requires a large labor.